Method and apparatus for drawing sheet-glass.



l. W. COLBURN. METHOD AND APPARATUS FOR DRAWI'N G SHEET GLASS.

APPLICATION FILEQ JAN-29. I908- RENEWED MAR. 25. I912.

Patented NOV. 16, 1915.

6 SHEETS-SHEET l.

JfM/M,

I 'I BY \5 ATTORNEYS 1 I I I I @luu ul. W. COLBURN. METHOD AND APPARATUSFOR DRAWING SHEE APPLICATION FILED IAN.29. 190a. RENEWED MAR.

T GLA 16, 1915. 6 HEETSSHEET 2- INVENTOR flaw F\G 5 BY H\$ ATTQRNEYS.

flu/v a Patented Nov l WVTNES$E3 w/ M 6- 5 M I. W. COLBURN. METHOD ANDAPPARATUS FOR DRAWING sum GLASS. APPLICATION FILED JAN-29, 1908. RENEWEDMAR. 25. 1912. 1 160,692, Patented Nov. 16, 1915.

6 SHEETS-SHEET 3.

I. W. COLBURN.

METHOD AND APPARATUS FOR DRAWING SHEET GLASS. APPLlCATlON FILED JAN.29,i908. RENEWED MAR. 26, I912.

Patented Nov. 16, 1915.

6 SHEETS-SHEET 4- Wrmzsscs FKS. 5

I. w. couaumv. v METHOD AND APPARATUS FOR DRAWING SHEET GLASS,

APPLICATION FILED JAN. 29'. 1908' RENEWED MAR. 26. I912.

Patented Nov. 16, 1915.

6 SHEETS-SHEET 5.

44 hf MW BY ms ATTOI'NLYS WITNESSES I. W. COLBURN METHOD AND APPARATUSFOR DRAWING SHEET GLASS. APPLICATION FILED JAN.29, I908. RENEWED MAR.26. I912.

Patented Nov. 16, 1915.

6 SHEETSSHEET 6.

FIG I5 INVENTOF? BY H Is ATTORNEYS UNITED STATES PATENT OFFICE.

IRVING W. 'COLBURN, 0F FRANKLIN, PENNSYLVANIA, ASSIGNOR, BY MESNEASSIGN- MENTS, TO TOLEDO GLASS COMPANY, OF TOLEDO, OHIO, A CORPORATIONOF OHIO.

METHOD AND APPARATUS FOR DRAWING SHEET-GLASS.

Specification of Letters Patent.

Patented Nov. 16, 1915.

Application filed January 29, 1908, Serial No. 413.296. Renewed March26, 1912. Serial No. 686.460.

To a?! whom it may concern:

Be it known that I, TRYING ll. COLBURN, of Franklin, Pennsylvania, haveinvented a new and useful Improvement in Methods and Apparatus forDrawing Sheet-Glass, which improvement is fully .set forth in thefollowing specification.

This invention relates to the art of drawing glass in sheet form from amass of molten glass.

When efforts are made to draw a sheet of glass from a molten mass ofglass there is a tendency upon the part of the sheet being drawn torapidly narrow, and unless means are provided for overcoming suchtendency the sheet will soon pull to a string or thread.

In a number of U. S. patents some of which were granted to me solely andsome jointly with Edgar \Vashburn, there are disclosed certain methodsand apparatus for drawing glass in sheet form, which methods and formsof apparatus include steps and mechanism for maintaining the width ofthe sheet during the drawing operation. These methods and forms ofapparatus disclosed in the patents aforesaid in practice have provedeflicient.

The method and apparatus constituting the present invention are designedto be used in connection with any suitable sheet glass drawingapparatus, and is particularly applicable to a machine of the characterset forth in my U. S. Patent 836,439, and my U. S. application SerialNo. 368,096, filed April 13, 1907.

The particular object of the present invention is to provide a methodand apparatus for avoiding or overcoming the narrowing of the sheet ofglass during the drawing operation, which method and apparatus shall bemore efficient in practice, simple to construct, and more readilyoperated than those known in the art prior to the present invention.

lVith these objects in view, the invention resides in the method ofdrawing sheet glass, which consists in preparing a mass of molten glasswhose temperature at the points where the edge portions of the sheetemerge from said molten mass is lower than is the tem perature of themolten mass as a whole, and particularly lower than the temperature ofthe molten mass along the line where the sheet of glass emerges from themolten mass between said points of lower temperature,

and then drawing a sheet of glass from said mass thus prepared with themain body portion of the glass emerging from the molten mass which hasthe higher temperature, while the edge portions of the sheet emerge orare drawn from the twoparts of the molten mass having the lowertemperature.

The invention further consists in regulating the temperature of themolten mass passing into the edge portions of the sheet and thetemperature of the molten mass passing into the main or middle portionof the sheet, so that the desired difference in temperature between themiddle and the edge portions may be maintained at the point where thebest results may be obtained. These will vary for different thicknessesof glass to be drawn and the rates of movement of the sheet during thedrawing operation.

The invention further consists in-applying a drawing action to the sheetas a whole, and in addition thereto applying a drawing action to theedge portions of the sheet, which drawing action may be regulated as toits rapidity of movement with relation to the drawing action exertedupon the sheet as a whole.

The invention further resides in a receptacle for a mass of moltenglass, combined with means for applying heat to the molten mass in thereceptacle, said receptacle and means being so constructed and combinedthat the portions of the molten mass in the receptacle from which theedge portions of the sheet are drawn shall be of a lower temperaturethan the middle or main portions of the receptacle from which the mainbody of the sheet of glass is drawn.

The invention further resides in c nnec-- tion with a suitablereceptacle for molten glass of the general character last described ofmeans acting to draw the sheet of glass as a whole from the molten mass,combined with drawing means acting solely upon the edge portions of thesheet'and to assist in the drawing operation so far as the edge portionsare concerned. Under some conditions, in order to obtain the bestresults, it may be found desirable to drive the main sheet-glass drawingmeans of the machine at a different rate of speed from that of the meansfor drawing the edge portions of the sheet, and with this object inview, means are provided whereby said edge portions may be operateu at adifferent speed from that of the main sheet-drawing portions; and alsomeans whereby the two sets of-edgedrawing'portions may, if desired, bedriven, the one at a difleren't rate of speed from the other.

The method of this invention may be practised in various forms withoutdeparting from the spirit of the invention, and the iiiventive'ideainvolved in the apparatus is capable of a variety of mechanicalexpressions. For the purpose of illustrating the invention, one 'forniof such apparatus is shown in the accompanying drawings, in Which-QFigure l is a broken detailed perspective; Fig. 2 is a top plan viewwith parts-broken away, andthe top or cover of the working chamberremoved; Fig. 3 is a transverse section on the line IIIIII of Fig. 2;Fig. 4 is a vertical and longitudinal section of the working chamber endof my continuous glass-working machine shown in my application No.368,096, with my improved .width-holding or maintaining device appliedthereto .instead of the width-holding or maintaining devices shown insaid application; Fig. 5 is a vertical transverse section on the lineV-V, Fig. 4, parts being shown in elevation Fig. 6 is a top plan view ofthe edge-engaging or supplemental drawing rolls "and their operatingmechanism; Fig. 7 is a side elevation of Fig. 6, and F ig." 8' is an endelevation, parts being shown in section; Fig. 9 is a broken sectionaldetail'illustrating the means for cooling the supplemental rolls; Fig.10 is a plan view of a working chamber, in which the cooler area fromwhich the edge portion of the sheet emerges differs somewhat in formfrom that shown in Fig. 2; Fig. 11. is a side elevation of the lowerportion of the edge of a sheet as it is being drawn in a working chambersuch as that shown in Fig. 10;- Fig. 12 is a sectional view on the ,lineXII-*XII. Fig. 11; and Figs. 13, 11

and .15 illustrate modified methods of obtamin'g .,the' cooleredge-forming areas.

Likeinumerals indicate like parts throughent the several views.

Figs. 1, 2, 3, 4, 5 and 10 all disclose sufficient portions of theworking chamber and drawing apparatus shown in my said application No.368,096, to clearly illustrate. the relation and application of mypresent invention thereto.

In carrying .out my improved process, any suitable form of sheet drawingmachine may be employed, but preferably I use the form of workingchamber and drawing apparatus shown in my said application. Sr. No.368,096." In the present invention.however, the revoluble spheres shownin said applica= tion are omitted-and the sheet is maintained of uniformwidth and the edge portions of the sha'fts3, 4, and through said boxespipes the sheet drawn by'the apparatus and in the manner now to bedescribed.

Referring to the drawings, and particularly'to Figs. 1, 2, 6, 7, 8 and9, two rolls 1 and 2, each preferably having a milled or knurledsurface, are mounted upontubular shafts 3, 4, respectively, which passrevolubly through bearings 5 and 6. Stufhng boxes 7 are provided on theexterior ends of 8, 8, pass within the tubular shafts 3, 4:, andterminate within the hollow rolls 1, 2, with-- in a short distance ofthe end of said rolls.

Water or other cooling fluid enters through the pipes S and is conductedto the rolls 1, 2,"and passes outward between the exterior of the pipes8 and the interior of the tubular shafts 3, 4, and passes by way of theoutlet 7 to the sewer or other suitable place of discharge. The bearing6 is rigidly mounted upon a suitable base 9, while bearing 5 is somounted on said base as to be capable of a slight horizontally rotativemovement, in order that the roll 1 may be withdrawn from or caused toapproach toward the roll' 2, as desired. A lever 10 is rigidly attachedto the bearing 5 and projects rearward, and at the outer end of saidlever is attached a spring connection 11, the normal action of which isto press the roll 1 toward the roll 2, as will be clearlyunderstood frominspection of Fig.6. Motion is imparted to shaft -l through the mediumof beveled gears 12 and 13, and is transmitted to shaft 3 through theinter-meshing spur gears 14 and 15, which are keyed to or otherwisesecured to the shafts 3 and 4 respectively. The beveled gear 12 is keyedto the shaft 12 to which power is applied for revolving the rolls. in amanner hereinafter set forth. As thus constructed, one set of thedrawing rolls is mounted upon each side of the working chamber of thec0ntinuous glass-drawing machine, the rolls being in proper position toengage the edge portions of the sheet being drawn.

The sheet 16 may be started by means of a bait or other suitable devicein any usual or well-known manner. and the drawing operation, ifpreferred, may be continued by means such as those fully set forth in mysaid application, Sr. No. 368,096. By the present invention, however,the edge por-.

tions of the sheet are drawn from a portion Referring to Figs. 1, 2, 3and l, by far the.

larger portion of the heat of the working chamber 18 is received throughthe fines 19 leading from the melting furnace 20, and through the fiues21 leading from the combustion chamber 22, and this heat takes thecourse indicated -by the numerous arrows in Figs. 2 and 3. A portion ofthe heated gases of combustion pass over and by the ends of therib-annihilating or skimming rolls 23. In addition to this, said rollsbecome highly heated and large quantities of heat are delivered byradiation to the areas of the Working chamber between the rolls as theyare revolved. It will be noted that bays-17, 17, i

are not so directly exposed to the action of anyvof this heat as are theother portions of the working chamber, and hence the temperature thereinis normally somewhat lower, and the glass therein consequently somewhatless plastic, than in .the main or central portion of the workingchamber. In fact, the glass in the bays 17 would soon becomecomparatively cold, and would be unworkable if means were not providedfor heating the glass within said bays. For this purpose I providesuitable burners, such as the Bunsen burners 24, 24, whereby heat may bedirected into the bays and upon the edgeforming area of the moltenglass, the temperature of the glass in said bays. however, being easilyregulated by controlling said burners.

As the sheet is drawn, the edge portions thereof are drawn from orformed from the molten glass in or immediately adjacent to said bays,where the glass is cooler, and consequently thicker or more viscous,than that in the main portion of the working chamber from which the mainbody of the sheet is drawn. From this it results that the edge portionsof the sheet are more tenacious-and less tractable or pliable than themain body of the sheet. and this results in the edge portions of thesheet as they emerge from the mass of molten glass being thicker thanthat of the main body of the sheet. It therefore. becomes necessary toemploy means for reducing the thickness of said edges, to

the end that they may be of substantially uniform thickness with thesheet proper, in order that the sheet will pass properly over thebending roll 25 (see Fig. 4) and down through the drawing chamber andannealing oven. Moreover, by reason of the lower temperature, with theconsequent increased viscosity and tenacity of the glass from which theedge portions of the sheet are drawn, the resistance incident to drawingthe edge portions of the sheet is greater than that obtaining in themain body or middle portions of the sheet, and in order to overcome thisadditional or increased resistance, and in order that the draft tensionupon the entire sheet may be uniform or equalized throughout the widthor trans- -verse section thereof, I employ the supplemental drawingrolls shown in Flgs. 6, 1,

8 and 9, and hereinbefore described. One set of said drawing rolls ismounted upon each side of the working chamber 18 in close proximity tothe mass of molten glass, and so positioned that each set of rolls is inposition to receive between them one edge of the sheet being drawn.while the shafts of said rolls extend horizontally outward, as clearlyshown in Figs. 2 and 5. For the purpose of driving the rolls. shafts 12,12, are attached each to a shaft 26 (see Fig. 5), each drivenindependently from variable speed pulleys 2T, 27, which are in turndriven by a jackshaft 28 to which motion is transmitted through avariable speed pulley E28, receiving motion from any suitable source ofpower. here shown as an electric motor 29. The other portions of thedrawing mechanism are driven by shaft 28 through the medium of belt 30and chain 31. I

By the arrangement of power transmission above described it will bevseen that the speed of each set of supplemental drawing rolls may beindividually varied through the respective pulleys 27. 27, transmittingpower to each set of rolls: also that the speed of the machine as awhole may be varied at the pulley 28, so that the speed of the variouselements of the mechanism may thus be harmonious and perfect cooperationbetween them secured.

As the sheet of glass forms from the molten mass, it assumes at theedges the form shown in Figs. 11 and 12. and as the thicker edgeportions 32 pass between the sets of rolls 1. :2, which revolve in thedirec tion shown by the arrows. such thicker portions are rolled down toa thickness corresponding to or somewhat greater than the main body ofthe sheet.

The rolls 1, 2. have knurled or milled peripheries to prevent theirslipping; and by regulating their peripheral speed by means of thevariable speed of pulleys 2T. 27. they may be caused to overcome all ofthe resistance due to the varying thickness and plasticity of the moltenglass entering into or forming the edge portions of the sheet below therolls. By this means the width of the sheet.

- intermediate the edge portions.

It will of course be understood that for the purpose of leading thewater or other cooling fluid into and from the rolls 1, 2, flexibleinlet conduits 8, 8', are connected to the pipes 8, and flexible outlet"pipes 8" are connected to, .th e, outlet points 7, all as clearlyillustrated in; Fig. 5.

In some constructions of working chamber, it may not lie necessary toprovide the inlets or bays 17. shown in Fig. 2, if the construction offurnace is 'such that the areas-ofthe molten glass from which the edgeportions of the sheet emerge will be cooler than that portion of themolten glass In that case, the edge portions of the sheet would be drawnfrom such cooler areas after the manner illustrated in Figs. 10 and 13.In Figs. ll and 15 there is shown an island of an upwardly projectingportion of refractory material fromwhich the edge portions of the sheetcould be drawn, while in Figs. 11 and 12 the edge portions of the sheetemerge from or immediately adjacent to the sides of the furnace itself.

I desire it distinctly understood that I do not wish to confine myselfto any particular form or construction of apparatus herein shown forproducing my edge-forming cooler areas, as any construction which willadmit of obtainingan edge-forming or cooler area of the nature hereinshown is within the spirit and scope of my invention. Moreover. whilethe burners 24 are shown herein as means by which the temperature ofsaid cooler areas is properly regulated independently of the surroundingmass of glass, said burners are shown-merely as illus trative of meanswhich may be employed for this purpose. and any means which wouldperform this function are within the scope of the invention.

\Vhat is claimed is: 1.'.Tl1e improrement in the: art t glass. workingwhich (on' inydrawin i of glass from a mass moltenglas is of lowertemperatureat l the;points,from which the edgefport'ons at; the sheetare drawn than itis alt gthe 'line.from which the main bodyfofftheslieet is draw said drawing being accomplished byea 'iplyi-ng adrawinge1 .t j the. sheet as a :wholejand additional drawing power to .theedgeportions of the SllQQt-* I i 2. The improvenintlin the art-of glassworking which consists preparingfla mass of molten glass. with sideportionscooler than the intermediate body of said mass, regulating theten'iperature of said side portions with relation to the temperature ofsaid intermediate portion while always maintaining it below that of saidintermediate portion, and then drawing the main body of a sheet of glassfrom said intermediate portion and the edge parts of the sheet from saidcooler side portions of the molten mass.

3. The improvement in the art of glass working which consists in drawinga sheet of glass from a mass of molten glass whose side portions arecooler than the middle or intermediate portions, and simultaneouslyapplying more drawing power to the edge portions of the sheet than tothe intermediateportion of said sheet.

4. The improvement in the art of glass working which consists in drawinga sheet of glass from a molten mass of glass whose temperature is higherwhere the main body of said sheet issues from the molten mass than atthe points where the side portions issue from said mass. said sheetbeing drawn by applying a uniform draft throughout the width'of thesheet and a further or additional draft at the edge portions of thesheet.

5.. The ii'nprovement in the art of glass working'which consists indrawing a sheet of glass from a mass of glass that is cooler at thepoints from which the edge portions of the sheet are drawn than it isalong the line from which the main body of the sheet is drawn. andapplying more drawing power to the edge portions than to the main bodyportion of the sheet.

6. The method of drawing sheet glass which consists in producingrelatively cool or less plastic areas in a .mass of molten glass.drawinga sheet of glass from said mass of molten glass, of causing theedge portions of said sheet to be formed from said areas. and intempering said areas independently of the surrounding mass.

7. The method of drawing sheet glass which consists in preparing a massof molten glass having one degree of temperature and plasticitythroughout the greater portion or area thereof and a relatively lowerdegree temperature and plasticity at two several 3 points thereof. andthen drawing a sheet of glass from said mass, the body of said sheetbeing formed from said area of higher temperature and degree ofplasticity and the edge portions'of said sheet being formed from saidpoints of lower temperature and degree of plasticity, and equalizing thedrawing tension throughout the transverse section of said sheet.

8.-In an apparatus for drawing sheet glass, the combination of a workingchamber and means for providing a mass of molten glass therein havingtwo several areas of a relatively lower degree of temperature andplasticity than the main body of the molten mass, with means for drawingthe main or central portion of a sheet of glass from that portion of themass having a relatively high degree of temperature and plasticity, andsupplemental means drawing the edge portions of the sheet of glass fromthose portions of the molten mass having a relatively lower degree oftemperature and plasticity.

9. In an appa atus for drawing sheet glass, the combination of a workingchamber for containing a mass of molten plastic glass, means forsupplying heat to-the main body of the molten mass in said chamber of ahigher degree than that supplied to two several areas thereof, wherebythe plasticity of the glass of said areas is of a less degree thanthatof the main body of the molten mass, with means for drawing a sheetof glass from said molten mass the edge portions of the sheet beingdrawn from said areas of lower temperature and plasticity and the mainbody of the sheet being drawn from the area of high temperature andplasticity.

tie sheet forming inor adjacent to said bays, the drafting means for theedge portions of the sheet being capable of a rate of movement differentfrom that of the drafting means for the intermediate-portion of thesheet.

11. In an apparatus for drawing sheet glass, the combination with aworking chamher for containing a mass of molten glass. means formaintaining the temperature of two oppositely disposed areas of themolten mass in said chamber at a degree below that of the main body ofthe molten mass, means for drawing a sheet of glass from said moltenmass, the edge portions of the sheet being drawn from said areas oflower temperature, and supplemental drawing means acting on the edgeportions of the sheet.

12. In an apparatus for drawing sheet glass, the combination of areceptacle for containing a mass of molten glass, means for applyingheat to the main body of the molten mass whereby said main body isheated to a higher degree of temperature than at two several points orareas thereof,

means for independently modifying the temperature of said several pointsor areas, and means for drawing the central portion of the sheet ofglass from said main body of the molten mass and the edge portions ofthe sheet from said points or areas of lower temperature.

13. In an apparatus for drawing sheet glass, the combination of areceptacle for containing a mass of molten glass, means for applyingheat to the main body" of the molten-mass in said receptacle of a highertemperature than that applied to certain lateral points or areas of saidmolten mass, means for regulating the temperature of said lateral pointsor areas, a main sheetdrawing means for drawing a sheet of glass fromsaid molten mass with its edge portions issuing from said areas of lowertemperature and its main portion issuing from the main body of themolten glass in said receptacle, and supplemental drawing means actingon the edge portions of the sheet during the drawing operation.

14. The improvement in the art of glass Working which consists inpreparing a mass of molten glass with side portions of a differenttemperature than the intermediate body of said mass, regulating thetempera ture of said side portions with relation to the temperature ofsaid intermediate body, and then drawing the main body of a sheet ofglass from said intermediate portion and the edge parts of the sheetfrom said side portions of the molten mass.

15. The improvement in the art of glass working which consists indrawing a sheet of glass from a mass of molten glass whose side portionsare of a different temperature than the middle or intermediate portion,and simultaneously applying more drawing power to one portion of thesheet than to the other.

16. In an apparatus for drawing sheet glass, the combination of areceptacle for containing a mass of molten glass, means for drawing asheet of glass therefrom, the means for drawing the central portion ofthe sheet being separate and independent from the means for drawing theedge portions of the sheet, and devices for driving the drawing meansfor the central portion of the sheet at a rate of speed diifering fromthat of the rate of speed at which the edge drawing means are driven.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

IRVING IV. (.OLBURN.

Witnesses:

Bass Lomsn BLACK,

l/VM. B. GRIIFEX.

Copies of this patent may be obtained for five cents'eaeh, by addressingthe Commissioner of Patents. Washington, I). G.

